The quadrupole moment of the 11(-) isomer in Pb-194 has been determined as \Q(s)\ = 4.48(86)e b via a new extension of the level mixing spectroscopy technique (LEMS). The new analysis technique allows one to take into account the influence of the electric quadrupole and the magnetic dipole interactions of two subsequent isomers on the angular distribution of the lower lying gamma-ray transitions. For each isomeric state the ratio of its quadrupole interaction frequency to its magnetic moment can be extracted from this double perturbation analysis, thus allowing to deduce their quadrupole moments provided that the electric field gradient and the magnetic moments are known.